Biomass refers to the weight of dry matter of living organisms (phytomass for plants and zoomass for animals) at any time per unit area. Plant biomass provides the primary energy source by absorbing small amount of solar energy through photosynthesis and acts as the foundation for all life forms. Nearly 75% of the rural population of India still depend on biofuels (firewood, agricultural residues, and cowdung) for meeting over 80% of their energy needs. An analysis of the distribution of the different energy forms in rural India reveals that the share of non- commercial energy is 65%, human energy 15% and commercial energy 20%. This clearly shows that 80% rural energy is met from traditional sources. In India, the total requirement of fuelwood is calculated to be about 150 million tonnes per annum whereas the annual availability is estimated to be about 50 million tonnes. A recent survey on energy sources and sectorwise consumption revealed that traditional fuel such as firewood (7.44 million tonnes of oil equivalent -42.99%), agro residues (1.510 million tonnes of oil- 8.72%), biogas conditioning (0.250 million tonnes of oil - 1.44%) accounts for 53.2% of total energy consumption in Karnataka ( T. V. Ramachandra et. al., 1997). This necessitates estimation of available bio resources and demand spatially available to evolve better management strategies and ensure renewability of resources. In this regard spatial tools such as GIS and Remote sensing data help immensely in providing geographically referenced spatial distribution of potential and demand.

Base maps of study site is prepared using the Survey of India (SOI) toposheets of scale 1:50 000. This includes administrative boundaries, road and drainage networks, contours and boundaries of vegetative areas (areas under forest department).LISS-III multispectral and PAN imageries were classified with ground data (collected using GPS). LISS-III has a spatial resolution of 23.5m and PAN with a spatial resolution of 5.8 m. By merging LISS-III multispectral bands with PAN helps in determining the spectral response patterns of vegetation. Merging helps in retaining the spectral advantage of multispectral bands while taking an advantage of PAN's spatial resolution. The spectral patterns of the different land cover were determined with a detailed mapping in 30 villages in Kolar taluk using GPS (Global Positioning System).This also helped in arriving at spectral response pattern of predominant tree species in Kolar taluk. This information was extrapolated to other taluks. This paper discusses an attempt in this regard to map Prosopis juliflora in Gauribidanur taluk based on training data collected from 30 villages of Kolar taluk and accuracy of mapping is about 88%. Prosopis juliflora - a fuelwood tree grows in basic soil (black cotton soil) and has the ability to lower soil pH.